Covers of this type have to be high quality in particular in the automotive industry in order to be usable in dash boards, thus they do not only have to be correctly sized but the surface structure and the print edges etc. also have to be made with very high quality.
Covers of this type typically do not only include a front plate providing the actual cover function but also a base element extending from the back side of the front plate in a depth direction so that the front plate and the base element together provide a three dimensional cover which has sufficient stability, can be easily handled and mounted and in which furthermore additional functions can be arranged.
For this purpose the front plate is typically made from a transparent material and is covered with a non light permeable layer on its front side wherein the non light permeable layer is only interrupted where a light permeable, in particular back lit portion shall be obtained in the cover. For this purpose the light impermeable layer is initially applied to the front plate so it covers the entire surface and is subsequently removed again in the desired portion e.g. through laser impact.
An additional function is forming pass through openings extending in depth direction of the cover, in particular of the base element of the cover, wherein the pass through openings on the front side can be closed or also left open by the front plate.
The frontal open pass through openings are used e.g. for inserting switches, operating buttons, which in turn can be again covers in the sense of the invention, or similar from the front side of the cover, while the dead or sack hole channels that are closed on the front side by the front plate have other functions and are often not only used for stabilizing the base element.
Thus e.g. portions of the cover, e.g. particular dead holes are back lit from the back side of the cover e.g. through LEDs which are arranged on a circuit board placed behind the cover in a respective position.
In particular when the a portion to be illuminated in the front plate of the cover is relatively small and the illuminating LED is relatively far behind the front plate due to the extension into the depth of the cover, e.g. 1-2 cm or more, the illumination effect on the front plate is too small.
For this purpose it is known to arrange a typically pin shaped like conductor made from plastic material in the dead hole of the cover, wherein the light conductor bridges the distance between the illuminating LED and the front plate which is light permeable in this portion in order to have a greater amount of light arrive at the front plate. Thus, the light conductor pins are made from a clear light permeable plastic material and the light conductor effect is typically comprised in that a reflection of incident light occurs at the lateral surfaces of the light conductor pin which extend in the extension direction of the light conductor pin and the light is reflected back into the light conductor.
In this context it is already known that the light conductor function of the light conductor pins is reduced when the light conductor pins are produced through filling the dead hole channel with clear plastic material through an injection molding method, thus the light conductor pins are melted together on their entire lateral surfaces together with the surrounding walls of the dead hole, thus the base element of the cover.
Melting the front face and/or the front portion of the side surfaces of the light conductor pin together in particular with the back side of the front plate, however, is harmless, since a passage of the light beam is particularly desirable at this location.
For this reason it is known to produce the light conductor pins on the other hand separately, in particular both of them through a plastic injection molding method and to subsequently insert the light conductor pins from behind into the open dead holes where they are typically interlocked through friction locking or a form locking configuration of light conductor pin and dead hole.
This, however, causes rather high logistical and assembly complexity, since the cover and the light conductor pins initially have to be produced separately possibly in the same injection molding tool, subsequently the light conductor pins have to be removed from the injection mold, stored in an intermediary manner, moved to the assembly location, correctly associated with the dead hole channels and have to be inserted into the dead hole channels. No matter whether this is performed manually or automatically the complexity is very high also for an automatic assembly particularly the investment for retrieval devices, assembly devices, transport devices, storage devices, in particular for the up to 20 light conductor pins per cover is very high.
Another problem is in this context is that covers of this type are often not planar with respect to a shape of a front side of the cover plate but have a curvature which can not only be provided in one spatial direction, but in two spatial directions as this is often the case for covers for dash boards for motor vehicles.
Since for reasons based on the injection molding technology this curvature of the front side of the front plate is typically also provided on the back side of the front plate in order to provide a even wall thickness for the front plate and the light conductor pins shall contact the back side of the front plate as precisely as possible with their front plate. This means that the light conductor pins to be used in a cover of this type, wherein the light conductor pins can be 20 or more are not identical to one another, are respectively slightly different in respect to length, curvature of the face, positioning of the interlocking elements and with respect to their longitudinal profiles.
This means that the light conductor pins are not exchangeable amongst one another with respect to the particular dead hole channels and due to the small dimensions of the light conductor pins, thus a length of 1-2 cm and a transversal extension of a few millimeters, the existing differences between the different light conductors are so small that they cannot be detected with bare eyes. This often leads to mix ups when the light conductor pins are subsequently mounted into the respective dead hole channels of the cover when the light conductor pins are not separated according to their types right from the beginning and even then mix ups can still occur.
However, when a wrong light conductor pin is pressed into a dead hole channel during assembly this is often not noticed during assembly since the physical differences between the different light conductors are very small.
This error typically only becomes apparent later when a subsequent assembly of the cover provided with the light conductors in a enveloping component is not possible or leads to damages at this location either at the cover or at the incorrectly inserted light conductor or at the receiving component enveloping the cover.
For a supplier of the cover to be integrated into a larger sub assembly this, however, causes great difficulties when he does not detect scrap due to wrongly inserted light conductor pins and delivers a faulty component of this type to his customer.